Development of Language and Symbol Use How Children Develop (3rd ed.) Siegler, DeLoache & Eisenberg Chapter 6 Guiding Questions What distinguishes symbols from language? What are the major components of language development? What is necessary for language to develop? What is babbling? What process do children undergo in order to learn language? What language skills do children possess at each stage of development? Using Language Involves... Language comprehension: Refers to understanding what others say (or sign or write) Language production: Refers to actually speaking (or signing or writing) to others Language Comprehension Language Production Major Components of Language Development Required Competencies for Learning Language Phonological Development Semantic Development Syntactic Development Pragmatic Development Phonological Development Phonological development: the acquisition of knowledge about phonemes, the elementary units of sound that distinguish meaning Semantic Development Semantic development: learning the system for expressing meaning in a language, beginning with morphemes, the smallest unit of meaning in a language Syntactic Development Syntactic development: learning the syntax or rules for combining words Pragmatic Development Pragmatic development: acquiring knowledge of how language is used, which includes understanding a variety of conversational conventions What is required for language to develop? A Human Brain A Human Environment 1. 2. A Human Brain The key to full-fledged language development is in the human brain: Language is a species-specific behavior Only humans acquire a communication system with the complexity, structure, and generativity of language. Language is also species-universal: Virtually all humans develop language Although some nonhuman primates have been trained to use signs or other symbols after concentrated effect by humans, there appears to be little evidence that they have acquired syntax. Brain-Language Relations Language processing involves a substantial degree of functional localization in the brain. The left hemisphere shows some specialization for language in infancy, although the degree of hemispheric specialization for language increases with age. Studies of individuals with brain damage resulting in aphasia provide evidence of specialization for language within the left hemisphere. Damage to Broca’s area, near the motor cortex, is associated with difficulties in producing speech. Damage to Wernicke’s area, which is near the auditory cortex, is linked to difficulties with meaning. Critical Period for Language Development To learn language, children must also be exposed to other people using language—spoken or signed. Sometime between age 5 and puberty, language acquisition becomes much more difficult and ultimately less successful. Difficulties feral children (such as Genie) have in acquiring language in adolescence. Comparisons of the effects of brain damage suffered at different ages on language. Language capabilities of bilingual adults who acquired their second language at different ages. Knowledge of the fine points of English grammar, for example, was related to the age at which individuals were exposed to English, but not to the total length of their exposure to the language. Bilingual Children More than half of the world’s children are exposed to more than one language. Children who are acquiring two languages do not seem to confuse them. They may initially lag behind monolingual children, although the course and rate of development for children learning one and two languages are similar. Bilingual children perform better on a variety of cognitive tests than do monolingual children Hence, the advantages of acquiring two languages outweigh the minor disadvantages. Hemispheric Differences in Language Processing Adults who learned a second language at 1 to 3 years of age show the normal pattern of greater left-hemisphere activity in a test of grammatical knowledge (darker colors indicate greater activation). Those who learned the language later show increased righthemisphere activity. Learning English as a Second Language A major debate in the U. S. has centered around the best classroom practice for children who are not yet fluent in English. One side advocates immersion into English. The other side recommends initial instruction in basic subjects in the native language with gradual increases in the amount of instruction in English. The latter approach can prevent semilingualism— inadequate proficiency in both languages. Test of the Critical-Period Hypothesis Performance on a test of English grammar by adults originally from Korea and China was directly related to the age at which they came to the United States and were exposed to English. The scores of adults who emigrated before the age of 7 are indistinguishable from those of native English speakers. A Human Environment Infant-directed talk (IDT) is the distinctive mode of speech that adults adopt when talking to babies and very young children. It is common throughout the world, but it is not universal Its characteristics include a warm and affectionate tone, high pitch, extreme intonation, and slower speech accompanied by exaggerated facial expressions Infants prefer IDT to speech directed to adults. What is the process by which language typically develops? Speech Perception Preparation for Production 3. First Words 4. Putting Words Together 5. Conversational Skills 6. Later Development 1. 2. 1. Speech Perception Fetuses appear to be sensitive to prosody, the characteristic rhythm, tempo, cadence, melody, intonational patterns, and so forth with which a language is spoken. Variations in prosody are in large part responsible for why languages sound so different from one another, and why speakers of the same language can sound so distinctive. Beyond prosody, speech perception also involves distinguishing among the speech sounds that make a difference in a given language. Categorical Perception of Speech Sounds Both adults and infants possess categorical perception of speech sounds (the perception of speech sounds as belonging to discrete categories). The two phonemes /b/ and /p/ occur along an acoustic continuum except that they differ in voice onset time (VOT)--the length of time between when air passes through the lips and when the vocal cords start vibrating. Categorical Perception of Speech by Adults When adults listen to a tape of artificial speech sounds that gradually change from one sound to another, such as /ba/ to /pa/ or vice versa, they suddenly switch from perceiving one sound to perceiving the other. Categorical Perception of Speech Sounds by Infants 1- and 4-month-olds were habituated to a tape of artificial speech sounds. Group habituated to /ba/ (VOT=20) dishabituated to /pa/ (VOT=40), and group habituated to /pa/ (VOT=60) continued to habituation to /pa/ (VOT =80) These findings suggest that, like adults, infants perceive speech categorically. Developmental Changes in Speech Perception Infants’ ability to discriminate between speech sounds not in their native language declines between 6 and 12 months of age. Six-month-olds from English-speaking families readily discriminate between syllables in Hindi (blue bars) and Nthlakapmx (green bars), but 10- to 12month-olds do not. Sensitivity to Regularities in Speech In addition to focusing on the speech sounds that are used in their native language, infants become increasingly sensitive to many of the numerous regularities in that language. Stress patterns: an element of prosody Distributional properties: in any language, certain sounds are more likely to appear together than are others Their own name: as early as 5 months they show the “cocktail party effect” 2. Preparation for Production At around 6 to 8 weeks of age, infants begin producing drawn out vowel sounds. As the repertoire of sounds they can produce expands, infants become increasingly aware that their vocalizations elicit responses from others and they begin to engage in dialogues of reciprocal sounds with their parents. Babbling Sometime between 6 and 10 months of age, infants begin to babble by repeating strings of sounds comprising a consonant followed by a vowel. A key component of the development of babbling is receiving feedback about the sounds one is producing. Congenitally deaf babies’ vocal babbling occurs late and is very limited, unless they are exposed to sign language, in which case they produce repetitions of hand movements that are components of ASL signs in a manner analogous to vocal babbling among hearing infants. As infants’ babbling becomes more varied, it conforms more to the sounds, rhythm, and intonation patterns of the language they hear daily. Silent Babbling Babies who are exposed to the sign language of their deaf parents engage in “silent babbling.” A subset of their hand movements differ from those of infants exposed to spoken language in that their slower rhythm corresponds to the rhythmic patterning of adult sign. Early Interactions Even before infants start speaking, they develop interactive routines similar to those required in the use of language for communication. Turn taking: apparent in simple games like “Give-and-Take” Intersubjectivity: the sharing of a common focus of attention by two or more people Joint attention: established when the baby and the parent are looking at and reacting to the same thing in the world around them Pointing: helps establish joint attention among infants older than 9 months of age, and by age 2, children use pointing to deliberately direct the attention of another person 3. First Words Infants first recognize words, then comprehend them, then begin to produce some of the words they have learned. By 5 months of age, infants can pick their own name out of background conversations. At 7 to 8 months of age, infants readily learn to recognize new words and remember them for weeks. In general, infants are better able to identify words when they are listening to IDT. The Problem of Reference Once infants can recognize recurrent units from the speech they hear, they must address the problem of reference, the associating of words and meaning. Infants may begin associating highly familiar words and referents by 6 months of age. By 10 months, children in the U.S. have comprehension vocabularies of about 11-154 words. Word Production Most infants produce their first words between 10-15 months of age. First words typically include names for people, objects, and events from everyday life. The period of one-word utterances is referred to as the holophrastic period, because the child typically expresses a “whole phrase” with a single word. Overextension, using a given word in a broader context than is appropriate, represents an effort to communicate despite a limited vocabulary. Adult Influences on Word Learning A spurt in vocabulary growth typically occurs at around 19 months, although there is great variability. The rate of vocabulary development is influenced by the sheer amount of talk that they hear. Caregivers play an important role in word learning by placing stress on new words and saying them in the final position in a sentence, by labeling objects that are already in the child’s attention, and by playing naming games. Repeating words also helps children acquire them. Variability in Language Development Style of acquisition: The set of strategies that young children enlist in beginning to speak. Children who use referential or analytic style analyze the speech stream into individual phonetic elements and words; their first utterances are often isolated, monosyllabic words. Those using expressive or holistic style pay more attention to the overall sound of language, its rhythmic and intonational patterns. Children using the wait-and-see style often begin to speak very late but then have a large vocabulary and quickly acquire more words. These different styles, however, have little if any effect on the ultimate outcome of the process of learning to talk. Children’s Contributions to Word Learning Fast mapping is the process of rapidly learning a new word simply from the contrastive use of a familiar and unfamiliar word. A number of assumptions (also called constraints or biases) guide children’s acquisitions of word meanings. The whole-object assumption leads children to expect a novel word to refer to a whole object, not a part. The mutual exclusivity assumption (also called the novel name–nameless category principle) leads children to expect that a given entity will have only one name. Meaning from Context Children use pragmatic cues, aspects of the social context used for word learning. These include the adult’s focus of attention and intentionality. Children also use the linguistic context in which novel words appear to help infer their meaning. Syntactic bootstrapping is a strategy in which children use the grammatical structure of whole sentences to figure out meaning. 4. Putting Words Together Most children begin to combine words into simple sentences by the end of their second year. Children’s first sentences are two-word utterances that have been described as telegraphic speech because nonessential elements are missing. Word order is preserved in early sentences, indicating children’s understanding of syntax. Once children are capable of producing four-word sentences, generally at around 2½ years of age, they begin to produce sentences containing more than one clause. Learning Grammar The strongest support for the idea that young children are learning grammatical rules comes from their production of word endings. Further evidence is provided by overregularization, speech errors in which children treat irregular forms of words as if they were regular. Parents play a role in children’s grammatical development by modeling correct grammar and expanding incomplete utterances. However, parents are more likely to correct factually inaccurate statements than grammatically incorrect ones. 5. Conversational Skills Much of very young children’s speech is directed toward themselves. Collective monologues: The content of each child’s turn having little or nothing to do with what the other child has just said. Conversations The extent to which children talk about the past increases dramatically over the preschool period. Whereas 3-year-olds include brief references to past events, 5-year-olds produce narratives, descriptions of past events that have the basic structure of a story. Parents scaffold their young children’s narratives by asking for elaboration. 6. Later Development The ability to sustain a conversation, which grew so dramatically in the preschool years, continues to improve for many years thereafter As children get older, their conversational turns become increasingly more related to what the other person has just said.